Natural Disasters

Cyclone Fani has been difficult to predict, but it’s not the first one

Cyclones Gaja, Titli and Ockhi had also intensified very quickly and taken weather forecasters and scientists by surprise

 
By Akshit Sangomla
Last Updated: Tuesday 07 May 2019
Cyclone Fani
Cyclone uproots thousands of trees in Odisha. Photo: Ashis Senapati Cyclone uproots thousands of trees in Odisha. Photo: Ashis Senapati

Cyclone Fani has had an interesting life since it first formed as a low-pressure area over the equatorial Indian Ocean and southeast Bay of Bengal on April 25, 2019. In short, it has been highly unpredictable for forecasters to pin down, especially with respect to its track and speed.

After forming and intensifying into a depression, Fani moved towards Sri Lanka and threatened to make landfall somewhere on the Tamil Nadu coast, according to forecasters. But then it changed direction and also decreased its pace to stay in the Bay of Bengal for more than eight days, all the while becoming more intense and ending up as an extremely severe cyclonic storm. Such cyclones sniff out warm waters on the sea surface and progressively become more intense.

Towards the end of its journey through the Bay of Bengal Fani changed character again. At first the India Meteorological Department (IMD) predicted that Fani will make landfall in Odisha on May 4, 2019 morning. Then IMD revised its estimate to the evening of May 3. Just yesterday, it again revised its estimate to afternoon but then the cyclone made landfall at 8.30 am in the state’s Puri district. The landfall carried ferocious winds with speeds ranging from 175-185 kilometres per hour (kmph). Occasional gusts can reach around 200 kmph.

The story is not over and there might be rapid intensification of the cyclone. Some meteorologists say Fani has sustained winds of 250kmph, which is just 10 km less than the 1999 Odisha Cyclone, the strongest in India's history. The 1999 cyclone had killed 10,000 people in Odisha alone. According to the Saffir-Simpson scale of categorising hurricanes with respect to their wind speeds, cyclone Fani is a category four hurricane.

Fani is also not the first such difficult-to-predict cyclone. In November-December 2017, cyclone Ockhi had taken an unusual track, forming in the western part of the Bay of Bengal, then swerving towards the Arabian Sea and finally ending up in Gujarat after seven days, all the time remaining at Sea. “This is a very unusual path taken by the cyclone. There have been some instances in the past when cyclones had developed on the Bay of Bengal and made their way to the west coast but these usually travel over the peninsula. Only a few have been recorded where the path has been completely over water,” M Mohapatra, an expert on cyclones and head of Regional Specialised Meteorological Centre (RSMC) of IMD had told Down to Earth.

The cyclone had also intensified very quickly, from a depression to a cyclone in a matter of 13 hours. This had taken weather forecasters and scientists by surprise. Cyclone Ockhi had killed 200 people in Tamil Nadu and Kerala.

“It was the first cyclone where such rapid intensification in a short span of time has ever been observed,” KJ Ramesh, director general of IMD, had said at a conference last year. The reasons for this were warm pockets of water on the ocean surface which could have been caused by global warming. Cyclones Gaja and Titli which impacted Tamil Nadu and Odisha last year also showed similar behaviour.

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